Air conditioning apparatus

ABSTRACT

An air conditioning apparatus including refrigeration means and heating means for selectively heating and cooling a plurality of zones, the apparatus being provided with separate heating means and separate refrigerant evaporator coils for each zone served thereby. High pressure, hot refrigerant vapor from the refrigerant compressor may be passed through a common refrigerant coil in heat exchange relation with liquid refrigerant from the refrigerant condenser to provide a load on the compressor when the refrigeration system is energized and the load imposed thereon by the separate evaporator coils is below the safe minimal compressor load. When desired, outside air may be introduced into the system through the common refrigerant coil, the air being cooled and dehumidified by the common refrigerant coil before passage to the individual zones.

United States Patent 119 Farney et al.

1451 July 3,1973

[ AIR CONDITIONING APPARATUS [75] Inventors: Samuel D. Farney; RussellE.

Wood, both of Syracuse, NY.

52 vs. C] 165/22, 165/27, 62/196 51 1 F24f 3/00 [58] Field of Search165/22, 27; 62/196 [5 6] References Cited UNITED STATES PATENTS 7/1936Lamb 62/117 10/1971 Miner l/l972 Toth 62/196 Primary ExaminerWilliam J.Wye Attorney-Harry G. Martin, Jr. and .l. Raymond Curtin [57] ABSTRACTAn air conditioning apparatus including refrigeration means and heatingmeans for selectively heating and cooling a plurality of zones, theapparatus being provided with separate heating means and separaterefrigerant evaporator coils for each zone served thereby. Highpressure, hot refrigerant vapor from the refrigerant compressor may bepassed through a common re-' frigerant coil in heat exchange relationwith liquid refrigerant from the refrigerant condenser to provide a loadon the compressor when the refrigeration system is energized and theload imposed thereon by the separate evaporator coils is below the safeminimal compressor load. When desired, outside air may be introducedinto the system through the common refrigerant coil, the air beingcooled and dehumidified by the common refrigerant coil before passage tothe individual zones.

9 Claims, 3 Drawing Figures PATENTED JUL 3 I975 SHEEIIBFZ INVENTORS D.FARNEY ATTORNEY SAMUEL RUSSELL E. WOOD PATENIEDJuL3 ms 3. 743.01 0

SHEET 2 BF 2 INVENTORS SAMUEL D. FARNEY RUSSELL E. WOOD ATTORNEY AIRCONDITIONING APPARATUS BACKGROUND OF THE INVENTION Self-contained airconditioning units such as roof-top units have become increasinglypopular in recent years. These units are ordinarily installed on theroof of a building for air conditioning the building. In manyinstallations, it is necessary to individually control the temperaturein a plurality of zones within a building served by a singleself-contained air conditioning unit. This has heretofore beenaccomplished by providing a large evaporator coil and a large heatingelement in the unit and by means of suitable dampers, providing heatedor cooled air to the individual zones. However, this requires operationof both the regrigeration system and the heating system even though onlyone of a plurality of zones might require cooling while the other zonesrequire heating or if only one zone might require heating while theother zones require cooling. Extremely uneconomical operation results.For example, in a unit capable of providing 120,000 Brisish thermalunits per hour (BTUH.) of cooling and 300,000 British thermal units perhour (BTUH.) of heating, the 300,000 BTUH. heating element may beenergized to satisfy one zone which might have a 50,000 BTUI-I. heatingload.

To obviate these problems, a self-contained air conditioning unit havinga plurality of heating elements and a plurality of refrigerantevaporator coils may be provided. However, to provide a minimal firstcost, it is desirable to employ a common compressorcondenser circuit tosupply the plurality of evaporator coils. While a multiple compressorarrangement employing compressor cylinder unloaders may be employed toprovide variable regrigeration capacity in response to the refrigerationload on the apparatus, it may not be practical to provide acompressorcondenser circuit having a minimum capacity equal to theminimum regrigeration load that might be imposed thereon.

SUMMARY OF THE INVENTION This invention relates to an air conditioningapparatus for use with a plurality of zones including fan means forcirculating air through the apparatus before passage thereof to theindividual zones, a refrigeration system for cooling the air circulatingthrough the apparatus including a compressor, a regrigerant condenseradapted to receive high pressure refrigerant from the compressor, aplurality of evaporator circuits, means for controlling the flow ofregrigerant from the condenser to the individual evaporator circuits inresponse to the temperature of the zones served thereby, and heatexchange means operably associated with the refrigeration system forpassage of refrigerant therethrough from the high pressure side of therefrigeration system to provide a load on the compressor which, inconjunction with the load imposed on the compressor by the evaporatorcircuits, is at least equal to the minimum capacity of the compressor.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of an airconditioning apparatus with portions of the cover broken away toillustrate internal components;

FIG. 2 is a view partly in section and partly in elevation of theapparatus of FIG. 1; and

FIG. 3 is a schematic view of the refrigeration circuit utilized in theapparatus illustrated in FIGS. 1 and 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings, thereis illustrated an air conditioning apparatus adapted to serve aplurality of zones in a building. To provide individual temperaturecontrol in each zone without the use of dampers, damper actuators, etc.,a plurality of direct-fired heat exchangers 2 for heating air and aplurality of refrigerant evaporator coils 4 are provided. While direct-fired heat exchangers are disclosed, it should be understood thatelectric resistance elements or other heating means could be utilized inplace of the direct-fired heat exchangers. A fan 6 and fan motor 7 areprovided to circulate air over the evaporator coils and heat exchangers.The unit illustrated is adapted to serve up to five individual zones. Toaccomplish this, baffles 8 are located to provide five separate airpassages downstream from fan 6. Each of the passages contains a singlerefrigerant evaporator coil 4 and two direct-fired heat exchangers 2.While a single evaporator coil and two direct-fired heat exchangers areillustrated in each air passage, it should be understood that anydesired number of evaporator coils 4 and heat exchangers 2 could belocated in each passage formed by baffles 8. Each of the individual airpassages is provided with a discharge opening 10, only one of which isvisible in FIG. 2.

The conditioned air from each discharge opening 10 may be supplied tothe individual zone to be served thereby. While it is contemplated thateach passage containing an evaporator coil 4 and two heat exchangers 2will serve one zone, it is to be understood that a number of dischargeopenings may be connected to a common duct to serve a zone requiring agreater heating and cooling capacity than could be provided by a singleevaporator coil and two heat exchangers.

Each heat exchanger 2 is provided with a fuel burner 12 and fuel valve14 which are adapted for energization by thermostatic control means, notshown, located in the zone served thereby.

Referring to FIG. 3, each evaporator coil is provided with refrigerantflow control means including a solenoid valve 13 and capillary 15, eachsolenoid valve being controlled by the thermostatic control meanslocated in the zone served thereby.

A refrigerant compressor 16 and condenser 18 are provided and suitablyconnected to evaporator coils 4 to provide liquid refrigerant thereto.An accumulator 19 is provided between the evaporator coils and thecompressor to prevent passage of liquid refrigerant to the compressor.Fan means 20 are provided to circulate ambient air over condenser 18 tocondense the refrigerant therein.

Air from the individual zones is returned to the apparatus throughopening 22 into a chamber 24. The chamber 24 is provided with dampers 26and 28. A second chamber 30 is provided with a heat exchanger 32 ashereinafter explained, and a damper 34 is also provided. To providefresh air to the individual zones, dampers 28 and 34 are opened to allowfan 6 to draw fresh air through outside air grille 36, heat exchanger32, and damper 34 for passage over heat exchangers 2 and evaporatorcoils 4. Filters 37 are provided to filter the air suppliedto fan 6.

Due to the restriction to air flow created by condenser 18, when dampers28 are open, the fan 20 draws air from the individual zones throughopening 22 and damper 28 and exhausts the air from the apparatus.

If it is desired to recirculate the air from the individual zones,dampers 28 and 34 may be closed and damper 26 may be opened so that fan6 draws air from chamber 24 rather than through grille 36, heatexchanger 32 and dampers 34. It should be understood that the dampers26, 28 and 34 may be modulated to provide any desired mixture ofrecirculated and fresh air to the individual zones rather than 100percent fresh air or 100 percent recirculated air as described.

The heat exchanger 32 is important for operation of the air conditioningapparatus at less than capacity. Referring to FIG. 3, when one or morezones is being cooled by the apparatus, liquid refrigerant may beprovided to heat exchanger 32 through thermal expansion valve 42 topre-cool and dehumidify the fresh air drawn in through grille 36.

If only one of the evaporator coils 4 is energized, the load on thecompressor may be below the safe minimum compressor loading, causingexcessively low suction pressures and insufficient refrigerant flow tothe compressor. To prevent this problem, heat exchanger 32 is alsoconnected to the compressor discharge through line 44. When compressorsuction pressure decreases to the minimal desired pressure, the pressurein a line 47 leading from the compressor inlet decreases accordingdly,and effects the opening of a bypass valve 46 disposed between compressorline 17 and line 44. The opening of valve 46 allows hot gas to pass tothe heat exchanger to increase the suction pressure and prevent freezeup of the evaporator coils 4 and 32. The thermal expansion valve 42feeding liquid refrigerant to heat exchanger 32 will open toautomatically provide sufficient liquid refrigerant flow to the heatexchanger to cool the hot refrigerant gas from the compressor.

This will increase suction pressure and the quantity of 40 refrigerantsupplied to the compressor to prevent low suction pressure and theresultant evaporator coil freeze up and provide sufficient refrigerantflow through the compressor for cooling purposes.

Thus, an air conditioning unit is provided which is capable ofsimultaneously satisfying both a heating load and a cooling load whilepreventing excessively low suction pressures when a minimal cooling loadis imposed thereon.

While we have described a preferred embodiment of our invention it is tobe understood that the invention is not limited thereto, but may beotherwise embodied within the scope of the following claims.

We claim:

1. An air conditioning apparatus adapted to treat a plurality of zones,said apparatus comprising:

A. a housing B. first fan means disposed within said housing for forcingair therethrough before passage thereof to the individual zones;

C. a refrigeration system within said housing for cooling the air forcedtherethrough, said refrigeration system including:

1. refrigerant compression means;

2. a refrigerant condenser adapted to condense high pressure refrigerantvapor from said compression means;

3. a plurality of evaporator circuits receiving refrigerant from saidcondenser, each circuit being adapted to serve an individual zone; and

4. means for controlling the flow of refrigerant from the condenser tothe individual evaporator circuits;

D. a plurality of separate heating means disposed within said housingserving separate zones;

E. baffle means forming a plurality of passages within said housing,each passage containing at least one of said evaporator circuits and atleast one of said heating means for passage of air thereover from saidfirst fan means, each of the air passages being adapted forcommunication with a zone served by the apparatus; and

F. damper means adapted to regulate the proportion of air returned fromthe individual zones and the proportion of outside air supplied to saidfirst fan means.

2. An air conditioning apparatus according to claim 1 further includingan outside air inlet formed in said housing;

a heat exchange coil disposed between said outside air inlet and saidfirst fan means; and,

means for passing refrigerant from said condenser through said heatexchange coil in heat exchange relation with outside air passedthereover for cooling and dehumidifying the outside air before passagethereof to said first fan means.

3. An air conditioning apparatus according to claim 1 and furtherincluding:

second fan means for circulating outside air over said condenser tocondense refrigerant therein; and

means forming a mixing chamber in said housing, said mixing chamberbeing supplied with return air from the zones served by the apparatus;

and wherein said damper means includes:

a first damper disposed between said mixing chamber and said first fanmeans for regulating the quantity of return air supplied to said fanmeans;

a second damper for communicating said mixing chamber with said secondfan means, said second damper being located for passage of air from saidmixing chamber to a location downstream from said condenser and upstreamfrom said second fan means for drawing return air from said mixingchamber and exhausting the return air to atmosphere;

an outside air inlet formed in said housing; and

a third damper disposed between said air inlet and said first fan means,said third damper regulating the amount of outside air supplied to saidfirst fan means.

4. An air conditioning apparatus according to claim 3 further includinga heat exchange coil disposed between said outside air inlet and saidfirst fan means; and

means for passing refrigerant from said condenser through said heatexchange coil in heat exchange relation with outside air passedthereover for cooling and dehumidifying the outside air before passagethereof to said first fan means.

5. An air conditioning apparatus for use with a plurality of zones, saidapparatus comprising:

A. a housing;

B. fan means for forcing air through said housing before passage thereofto the individual zones;

C. a refrigeration system for cooling the air forced through theapparatus, said refrigeration system including:

l. compression means;

2 a refrigerant condenser adapted to receive high pressure refrigerantfrom said compression means;

3. a plurality of evaporator circuits receiving refrigerant from saidcondenser and transmitting refrigerant to said compression means; and

4. means for controlling the flow of refrigerant from said condenser tothe individual evaporator circuits and;

D. heat exchange means operatively associated with said refrigerationsystem for passage of refrigerant therethrough from the high pressureside of the refrigeration system to provide a load on said compressionmeans which, in conjunction with the load imposed on said compressionmeans by said evaporator circuits, is at least equal to the minimumcapacity of said compression means.

6. An air conditioning apparatus according to claim 5 further includingmeans for introducing outside air into said system across said heatexchange means; and

refrigerant expansion means for regulating flow of refrigerant from saidcondenser to said heat exchange means.

7. An air conditioning apparatus according to claim 6 further includingvalve means adapted to regulate flow of refrigerant vapor from saidcompression means to said heat exchange means to increase the load onsaid heat exchange means so that'the load imposed thereby on saidcompression means is at least equal to the minimum capacity of saidcompression means.

8. An air conditioning apparatus according to claim 5 further includingrefrigerant expansion means for regulating the flow of refrigerant fromsaid condenser to said heat exchange means, and valve means adapted toregulate flow of refrigerant vapor from said compression means to saidheat exchange means to provide a minimum load on said compression means.

9. An air conditioning apparatus including:

A. a compressor for compensating hot gaseous refrigerant;

B. a condenser operatively connected to said compressor for condensingrefrigerant received from said compressor;

C. evaporator means for absorbing heat from the space surrounding saidevaporator, said evaporator receiving refrigerant from said condenserfor transfer to said compressor; and

D. means for maintaining a minimum load on said compressor said meanscomprising:

1. heat exchange means for normally receiving refrigerant flow from saidcondenser;

2. means actuable for transmitting refrigerant from the discharge sideof said compressor to said heat exchange means to provide a load on saidcompressor; and

3. means responsive to minimum load conditions on said compressor foractuating said transmitting means.

1. An air conditioning apparatus adapted to treat a plurality of zones,said apparatus comprising: A. a housing B. first fan means disposedwithin said housing for forcing air therethrough before passage thereofto the individual zones; C. a refrigeration system within said housingfor cooling the air forced therethrough, said refrigeration systemincluding:
 1. refrigerant compression means;
 2. a refrigerant condenseradapted to condense high pressure refrigerant vapor from saidcompression means;
 3. a plurality of evaporator circuits receivingrefrigerant from said condenser, each circuit being adapted to serve anindividual zone; and
 4. means for controlling the flow of refrigerantfrom the condenser to the individual evaporator circuits; D. a pluralityof separate heating means disposed within said housing serving separatezones; E. baffle means forming a plurality of passages within saidhousing, each passage containing at least one of said evaporatorcircuits and at least one of said heating means for passage of airthereover from said first fan means, each of the air passages beingadapted for communication with a zone served by the apparatus; and F.damper means adapted to regulate the proportion of air returned from theindividual zones and the proportion of outside air supplied to saidfiRst fan means.
 2. a refrigerant condenser adapted to condense highpressure refrigerant vapor from said compression means;
 2. An airconditioning apparatus according to claim 1 further including an outsideair inlet formed in said housing; a heat exchange coil disposed betweensaid outside air inlet and said first fan means; and, means for passingrefrigerant from said condenser through said heat exchange coil in heatexchange relation with outside air passed thereover for cooling anddehumidifying the outside air before passage thereof to said first fanmeans.
 2. means actuable for transmitting refrigerant from the dischargeside of said compressor to said heat exchange means to provide a load onsaid compressor; and
 3. a plurality of evaporator circuits receivingrefrigerant from said condenser and transmitting refrigerant to saidcompression means; and
 3. means responsive to minimum load conditions onsaid compressor for actuating said transmitting means.
 3. An airconditioning apparatus according to claim 1 and further including:second fan means for circulating outside air over said condenser tocondense refrigerant therein; and means forming a mixing chamber in saidhousing, said mixing chamber being supplied with return air from thezones served by the apparatus; and wherein said damper means includes: afirst damper disposed between said mixing chamber and said first fanmeans for regulating the quantity of return air supplied to said fanmeans; a second damper for communicating said mixing chamber with saidsecond fan means, said second damper being located for passage of airfrom said mixing chamber to a location downstream from said condenserand upstream from said second fan means for drawing return air from saidmixing chamber and exhausting the return air to atmosphere; an outsideair inlet formed in said housing; and a third damper disposed betweensaid air inlet and said first fan means, said third damper regulatingthe amount of outside air supplied to said first fan means.
 3. aplurality of evaporator circuits receiving refrigerant from saidcondenser, each circuit being adapted to serve an individual zone; and4. means for controlling the flow of refrigerant from the condenser tothe individual evaporator circuits; D. a plurality of separate heatingmeans disposed within said housing serving separate zones; E. bafflemeans forming a plurality of passages within said housing, each passagecontaining at least one of said evaporator circuits and at least one ofsaid heating means for passage of air thereover from said first fanmeans, each of the air passages being adapted for communication with azone served by the apparatus; and F. damper means adapted to regulatethe proportion of air returned from the individual zones and theproportion of outside air supplied to said fiRst fan means.
 4. An airconditioning apparatus according to claim 3 further including a heatexchange coil disposed between said outside air inlet and said first fanmeans; and means for passing refrigerant from said condenser throughsaid heat exchange coil in heat exchange relation with outside airpassed thereover for cooling and dehumidifying the outside air beforepassage thereof to said first fan means.
 4. means for controlling theflow of refrigerant from said condenser to the individual evaporatorcircuits and; D. heat exchange means operatively associated with saidrefrigeration system for passage of refrigerant therethrough from thehigh pressure side of the refrigeration system to provide a load on saidcompression means which, in conjunction with the load imposed on saidcompression means by said evaporator circuits, is at least equal to theminimum capacity of said compression means.
 5. An air conditioningapparatus for use with a plurality of zones, said apparatus comprising:A. a housing; B. fan means for forcing air through said housing beforepassage thereof to the individual zones; C. a refrigeration system forcooling the air forced through the apparatus, said refrigeration systemincluding:
 6. An air conditioning apparatus according to claim 5 furtherincluding means for introducing outside air into said system across saidheat exchange means; and refrigerant expansion means for regulating flowof refrigerant from said condenser to said heat exchange means.
 7. Anair conditioning apparatus according to claim 6 further including valvemeans adapted to regulate flow of refrigerant vapor from saidcompression means to said heat exchange means to increase the load onsaid heat exchange means so that the load imposed thereby on saidcompression means is at least equal to the minimum capacity of saidcompression means.
 8. An air conditioning apparatus according to claim 5further including refrigerant expansion means for regulating the flow ofrefrigerant from said condenser to said heat exchange means, and valvemeans adapted to regulate flow of refrigerant vapor from saidcompression means to saId heat exchange means to provide a minimum loadon said compression means.
 9. An air conditioning apparatus including:A. a compressor for compensating hot gaseous refrigerant; B. a condenseroperatively connected to said compressor for condensing refrigerantreceived from said compressor; C. evaporator means for absorbing heatfrom the space surrounding said evaporator, said evaporator receivingrefrigerant from said condenser for transfer to said compressor; and D.means for maintaining a minimum load on said compressor said meanscomprising: